in Journal of Clinical Endocrinology and Metabolism (2014), 99(3), 453-7

Background: Parathyroid carcinoma (PCa) is rare and often difficult to differentiate initially from benign disease. Because PCa oversecretes amino PTH that is detected by third-generation but not by ... [more ▼]

Background: Parathyroid carcinoma (PCa) is rare and often difficult to differentiate initially from benign disease. Because PCa oversecretes amino PTH that is detected by third-generation but not by second-generation PTH assays, the normal generation PTH ( 1) is inverted in PCa (ie, 1). Objective: The objective of the investigation was to study the utility and advantages of automated generation PTH ratio measurements using the Liaison XL platform over existing manual techniques. Setting: The study was conducted at a tertiary-referral academic center. Design: This was a retrospective laboratory study. Subjects: Eleven patients with advanced PCa (mean age 56.0 y). The controls were patients with 1°-hyperparathyroidism (n 144;meanage 53.8 y), renal transplantation (n 41;meanage 50.6 y), hemodialysis (n 80; mean age 65.2 y), and healthy elderly subjects (n 40; mean age 72.6 y). Results: The median (interquartile range) generation PTH ratio was 1.16 (1.10 –1.38) in the PCa group, which was significantly higher than the control groups: 0.74 (hemodialysis, 0.71–0.75), 0.77 (renal transplant, 0.73–0.79), 0.80 (healthy elderly, 0.74–0.83), and 0.76 (1°-hyperparathyroidism, 0.74–0.78). An inverted -generation PTH ratio ( 1) was seen in 9 of 11 PCa patients (81.8%) and in 7 of 305 controls (2.3%), 3 of 80 hemodialysis (3.8%), and 4 of 144 1°-hyperparathyroidism patients (2.8%). Of four PCa patients who had a normal PTH ratio with the manual method, two had an inverted -generation PTH ratio with the automated method. Conclusions: Study of the -generation PTH ratio in large patient populations should be feasible using a mainstream automated platform like the Liaison XL. The current study confirms the utility of the inverted -generation PTH ratio as a marker of PCa (sensitivity: 81.8%; specificity: 97.3%). [less ▲]

Introduction: Paraneoplastic hypercalcemia is a sign of poor prognosis, as it is particularly resistant to the usual hypocalcemic treatments. Observation: In 2009, a well differentiated pancreatic ... [more ▼]

Introduction: Paraneoplastic hypercalcemia is a sign of poor prognosis, as it is particularly resistant to the usual hypocalcemic treatments. Observation: In 2009, a well differentiated pancreatic neuroendocrine tumor (Ki-67= 2%) is diagnosed in a 52-year-old diabetic man. The tumor is revealed with a splenic and hepatic carcinomatosis. Plasmatic calcium was: 3.54 mmol/L (2.15 - 2.6). Biology showed hypophosphatemia, PTH < 4 ng/ml, high 1-25 OH VitD, calcitonin: 1016 ng/ml (< 12 ng/ml). He had hypercalciuria and hypophosphaturia. He received for two years several cycles of Streptozotocin-ADRIAMYCIN and FOLFOX, with partial control of the tumor mass and calcium levels. In 2012, calcitonin levels are 29 ng/ml whereas calcemia is 3.17 mmol/L. Hypercalcemia is refractory to hyperhydration, diuretics, corticosteroids, and bisphosphonates therapy. Cinacalcet (Mimpara) is prescribed up to 120 mg/day (PO). Calcemia decreases gradually from 3 to 2.87 and then 2.76 mmol/L. PTH and calcitonin-the tumor mass remain unchanged. After two months of Cinacalcet treatment, Sunitinib (Sutent) 37.5 mg per day was added. During the third month, calcium levels dropped to 2.09 mmol/L and PTH raised to 78 pg/ml, requiring discontinuation of Mimpara. Calcitonin normalized, with a further improvement over pancreatic and metastatic lesions. Conclusion: Cinacalcet is a Calcium Sensing Receptor oral agonist. Cinacalcet hypocalcemic effects have not been previously documented in pancreatic paraneoplastic hypercalcemia. In our patient, Cinacalcet has significantly improved cancer prognosis: this drug could be a new alternative in paraneoplastic hypercalcemia. [less ▲]

Objective: Genetic disorders of calcium metabolism arise in a familial or sporadic setting. The calcium-sensing receptor (CaSR) plays a key role in maintaining calcium homeostasis and study of the CASR ... [more ▼]

Objective: Genetic disorders of calcium metabolism arise in a familial or sporadic setting. The calcium-sensing receptor (CaSR) plays a key role in maintaining calcium homeostasis and study of the CASR gene can be clinically useful in determining etiology and appropriate therapeutic approaches. We report two cases of novel CASR gene mutations that illustrate the varying clinical presentations and discuss these in terms of the current understanding of CaSR function. Patients and Methods: A 16 yr-old patient had mild hypercalcemia associated with low-normal urinary calcium excretion and normal-to-high parathyroid hormone (PTH) levels. Because of negative family history, familial hypocalciuric hypercalcemia (FHH) was originally excluded. The second patient was a 54 yr-old man with symptomatic hypocalcemia, hyperphosphatemia, low PTH, and mild hypercalciuria. Familial investigation revealed the same phenotype in the patient's sister. The coding region of the CaSR gene was sequenced in both probands and their available first-degree relatives. Results: The first patient had a novel heterozygous inactivating CASR mutation in exon 4, which predicted a p.A423K change; genetic analysis was negative in the parents. The second patient had a novel heterozygous activating CASR mutation in exon 6, which predicted a p.E556K change; the affected sister of the proband was also positive. Conclusions: We reported two novel heterozygous mutations of the CASR gene, an inactivating mutation in exon 4 and the first activating mutation reported to date in exon 6. These cases illustrate the importance of genetic testing of CASR gene to aid correct diagnosis and to assist in clinical management. [less ▲]